Locking mechanism for pliers and the like



April 1957 J- D. BOTHUM 3,313,190

LOCKING MECHANISM FOR PLIERS AND THE LIKE Filed Oct. 22, 1965 INVENTOR. JoH/v BoTHc/M ATTORNEYS tive.

United States Patent Ofifice 3,313,19h Patented Apr. 11, 1957 3,313,190 LGCEQNG MECHANTSM FOR PMERS AND TEE LIKE John David Bothnm, 604- Commercial St, Albert Lea, Minn. 56007 Filed Get. 22, 1965, Ser. No. 591,341 2 Ciaims. (El. 81323) This invention pertains to a new and improved locking mechanism for pliers and the like and more particularly to a locking mechanism which positively maintains the pliers in a gripping position once they are clamped on to an object.

Several locking mechanisms for pliers have been described previously but none of these devices operated well and, therefore, never became popular. Foremost of these devices are the lever locking device set forth in Patent No. 1,944,116 and the actuating and locking means for the handles of plier-type tools set forth in Reissue Patent No. Re. 23,761. In both of these patents a device is described which included a rod-like member extending from one handle through an opening in the other handle. A pivotally mounted member having a hole therethrough is mounted on the inner surface of the other handle so that the rod-like member passes through the hole therein. A spring means biases the pivotally mounted member so that it pivots a sufiicient distance to frictionally engage the rod-like member and lock the pliers in a clamped or normal position.

In Patent No. 1,944,116 the pivotal member set forth is constructed of a thin material which quickly breaks or wears out, thereby rendering the locking device inopera- In the Reissue Patent Re. 23,761 the axis of the hole through the pivotal member is inclined from a line extending perpendicular to the longitudinal axis of the pivotal member. This provides gripping edges for fric tionally engaging the rod-like member. It has been found that a slight amount of wear on the edges of the hole through this pivotal member quickly renders the blocking mechanism inoperative. It appears that a slight amount of wear on the edges of the hole tend to make the axis of the hole incline more toward the perpendicular. Also, any wear on the edges of the rod-like member causes separation of the rod-like member from the gripping edges of the pivotally mounted member so the frictional engagement is below a minimum allowable value and the locking means is inoperative. This occurs because the rod-like member engages the gripping edge nearest the ivotal mounting point during proper operation but after slight wear this edge becomes separated from the rodlike member and movement thereof has a tendency to increase, rather than decrease, the separation.

In the present invention, a pair of pliers or the like is provided with a locking mechanism including an arcuate shaped rod-like member integrally attached to one of the handles and passing through an opening in the other handle. A pivotal member is attached to the other handle and has an opening there, with an axis substantially perpendicular to the longitudinal axis of the pivotal member, which received the rod-like member therethrough. The pivotal member has a substantially reduced cross-section adjacent at least portions of the opening which act as gripping edges to frictionally engage the rod-like member and lock the pliers in a clamped position. The reduced cross-section may be produced in a number of ways, such as counter-sinking the opening from either side or from a single side. In general the portions of the pivotal member having a reduced crosssection adjacent the opening therethrough will be in a plane substantially parallel with the plane of the pivotal member. 1

The present locking mechanism, which operates in a fashion vastly superior to anything previously devised, is an improvement over the prior art. The pivotal member of the present invention is constructed of material having a relatively large cross-section so that it will not easily break or bend. Also, the present locking mechanism continues to operate in a superior fashion in spite of wear and the like. Also, the present locking mechanism has a positive action which will not fail, even after long, hard use.

It is an object of the present invention to provide an improved locking mechanism for pliers and the like.

It is a further object of the present invention to provide a locking mechanism which will not become inoperative after the parts are worn slightly.

It is a further object of the present invention to provide a locking mechanism for a pliers and the like which is extremely rugged and will not break or bend, thereby, rendering the mechanism inoperative.

These and other objects of this invention will become apparent to those skilled in the art upon consideration of the accompanying specification, claims and drawings.

Referring to the drawings, wherein like characters indicate like parts throughout the figures:

FIG. 1 is a view in side elevation of the present invention fixedly attached to a plier, the dotted lines illustrating a different position;

FIG. 2 is an end view of the device illustrated in FIG. 1;

FIG. 3 is a view similar to FIG. 1, parts thereof removed and parts thereof broken away and shown in section;

FIG. 4 is a sectional view as seen from the line 4-4 of FIG. 3;

FIG. 5 is a sectional view as seen from the line 55 of FIG. 3;

FIG. 6 is an enlarged detailed view shown in section of the opening in the pivotal member; and

FIG. 7 is an enlarged detailed view shown in section of a different embodiment of the opening in the pivotal member.

Referring to the drawing, the numeral 10 generally designated a pair of pliers having a pair of cooperating jaws 11 and 12 formed at the ends of a pair of cooperating handles 13 and 14 respectively. The handle 13 with the integral jaw 11 and handle 14- with the integral jaw 12 are pivotally attached together in the usual manner by means of a bolt 15.

An arcuate member forms an integral part of the handle 14 adjacent the end thereof. The arcuate member 2!) extends from the handle 14 toward the handle 13. The center of an imaginary circle having the arcuate member 20 in the circumference thereof lies approximately along the longitudinal axis of the bolt 15. An opening 21 in the handle 13 is adapted to receive the arcuate member 21) therethrough.

The end of the handle 13 has a portion 25 which is turned inwardly toward the handle 14 and has an opening 26 therein. An actuating lever 27 has a portion 28 adjacent one end thereof tapered to fit into the opening 26 in the portion 25. Some device, such as the score marks 29 in the portion 28, is utilized to maintain the actuating lever 27 pivotally mounted within the opening 26 in the portion 25. An opening 313 in the actuating lever 27 is positioned so that the arcuate member 20 extends therethrough. A cross-section of the opening 30 can be seen more clearly in FIG. 6.

Referring to FIG. 6, the opening 30 in the actuating lever 27 has an inner diameter somewhat larger than the dimensions of the arcuate lever 20 along a radius of the arc. The axis of the opening 31), represented by the broken line 31, is substantially perpendicular to the longitudinal axis of the actuating lever 27. The edges of the opening 30 on either side of the actuating lever 27 are beveled or countersunk to provide portions 32 of the actuating lever 27 having a substantially reduced crosssection. In FIG. 7, a second embodiment of the opening 30 and in the actuating lever 27 is illustrated. A prime has been added to the numbers to indicate that a ditferent embodiment is illustrated. In FIG. 7, the opening 39 is provided in the actuating lever 27' along an axis 31 perpendicular to the longitudinal axis of the actuating lever 27'. Portions 32' of the actuating lever 27 having a substantially reduced cross-section are provided about the edges of the opening 36' by counter-boring the opening 30' to a substantial depth from one of the surfaces of the actuating lever 27'. It should be understood that portions 32 having a reduced cross-section might also be provided by counter-boring the actuating lever 27' from both surfaces, or in any other fashion well-known to those skilled in the art.

The opening 21 in the handle 13 is counterbored from the inner surface to receive a cylindrical compression spring 35 which is positioned between the handle 13 and the actuating lever 27. The spring 35 forces the actuating lever 27 outwardly from the handle 13 so that the portions 32 thereof are in frictional engagement with the arcuate member 2%. Thus, the actuating lever 27 has a first position A, illustrated in full lines in FIG. 3, in which the portions 32 thereof engage the arcuate member 2% preventing movement of the handles 13 and 14 away from each other, or locking the jaws 11 and 12 in a clamped position. In the second position of the actuating lever 27, illustrated in dotted lines in FIG. 3 and designated B, the opening 39 therein is substantially aligned with the opening 21 in the handle 13 and the arcuate member 2%) slides freely therethrough.

Referring to FIG. 3, it should be noted that upward movement of the arcuate member 20 through the opening 30 in the actuating lever 27 produces a binding effect between the portions 32 of the actuating lever 27 and the edges of the arcuate member 29, due to the frictional engagement of the portions 32 and the bias of the spring 35. This binding effect tends to cause the actuating lever 27 to rotate about the portion 25 of the handle 13 in a clockwise direction. This tendency of the actuating lever 27 to rotate locks the handles 13 and 14 in the position shown. It should be noted that even though the portions 32 wear, this locking action will not be impaired since the actuating lever 27 will simply rotate slightly farther in the clockwise direction. Referring to FIG. 6, it can be seen that any wear on the portion 32 will slightly increase the cross-section thereof, as well as the inner diameter of the opening 30, and have little or no effect on the operation thereof. Similarly, referring to FIG. 7, any wear on the portion 32' will not even increase the crosssection thereof but will simply increase the diameter of the opening 30 slightly and, thus, will have substantially no effect on the operation thereof. In both cases the axes of the openings 3%} and 31' will remain perpendicular to the longitudinal axes of the actuating levers 27 and 27' respectively and the portions 32 and 32' will maintain substantially the same angular relationship to the arcuate members 2% and 28'. In contrast, it should be noted that the axis of an opening through an actuating lever which is inclined at an angle to the perpendicular (as in the prior art) will gradually appear to approach the perpendicular as the opening is enlarged by wear and the gripping edges will not frictionally engage the arcuate member. Thus, in a very short time the prior art device becomes inoperative while the present device is unimpaired.

While I have shown and described a specific embodiment of this invention, further modifications and improvements will occur to those skilled in the ar I desire it to be understood, therefore, that this invention is not limited to the particular form shown and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.

What is claimed is:

1. Locking mechanism for a gripping type tool having a pair of cooperating pivoted handles comprising:

(a) an arcuate shaped member fixedly attached to one of said handles and extending toward the other of said handles;

(b) an opening in said other handle for receiving said arcuate shaped member therethrough;

(c) an actuating lever pivotally attached adjacent one end to said other handle;

(d) an opening through said actuating lever having an axis substantially perpendicular thereto for receiving said arcuate shaped member therethrough, said actuating lever having generally inwardly converging edges around said opening for frictionally engaging said arcuate shaped member when said actuating lever is in a first position and allowing free movement thereof when said actuating lever is in a second position; and

(e) spring means biasing said actuating lever normally into said first position.

2. A locking mechanism for a gripping type tool having a pair of cooperating pivoted handles substantially as set forth in claim 1 wherein the edges of the actuating lever around the arcuate shaped member receiving opening substantially converge into a plane lying parallel to the plane of said actuating lever.

References Cited by the Examiner UNITED STATES PATENTS WILLIAM FELDMAN, Primary Examiner.

MILTON S. MEI-IR, Examiner. 

1. LOCKING MECHANISM FOR A GRIPPING TYPE TOOL HAVING A PAIR OF COOPERATING PIVOTED HANDLES COMPRISING: (A) AN ARCUATE SHAPED MEMBER FIXEDLY ATTACHED TO ONE OF SAID HANDLES AND EXTENDING TOWARD THE OTHER OF SAID HANDLES; (B) AN OPENING IN SAID OTHER HANDLE FOR RECEIVING SAID ARCUATE SHAPED MEMBER THERETHROUGH; (C) AN ACTUATING LEVER PIVOTALLY ATTACHED ADJACENT ONE END TO SAID OTHER HANDLE; (D) AN OPENING THROUGH SAID ACTUATING LEVER HAVING AN AXIS SUBSTANTIALLY PERPENDICULAR THERETO FOR RECEIVING SAID ARCUATE SHAPED MEMBER THERETHROUGH, SAID ACTUATING LEVER HAVING GENERALLY INWARDLY CONVERGING EDGES AROUND SAID OPENING FOR FRICTIONALLY ENGAGING SAID ARCUATE SHAPED MEMBER WHEN SAID ACTUATING LEVER IS IN A FIRST POSITION AND ALLOWING FREE MOVEMENT THEREOF WHEN SAID ACTUATING LEVER IS IN A SECOND POSITION; AND (E) SPRING MEANS BIASING SAID ACTUATING LEVER NORMALLY INTO SAID FIRST POSITION. 